Plate type hydraulic valve



May 8,

Filed Jan. 9, 1953 D. vz. ERLE 2,744,540

PLATE TYPE HYDRAULIC VALVE 2 Sheets-Sheet l Za 0/ 0 27 if o 6.6- T 2# a27 INVENToR.

D. Z. ERLE 64l 29 22 BY A l. f p

ATTORNEY May 8, 1956 D. z. ERLE 2,744,540

PLATE TYPE HYDRAULIC VALVE Filed Jan. 9, 1953 2 Sheets-Sheet 2 9INVENTOR/ 0.2. ERLE ATTORNEY United States Patent O PLATE TYPE HYDRAULICVALVE Donald Zaner Erle, Van Nuys, Calif., assignor to Bendix AviationCorporation, North Hollywood, Calif., a corporation of DelawareApplication January 9, 1953, Serial No. 330,574

11 Claims. (Cl. 137-624) This invention relates to hydraulic valves ofthe plate typeA involving ported, flat sliding sealing surfaces, asdistinct from poppet valves and from shuttle valves having cylindricalsealing surfaces.

An object of the invention is to provide a plate type valve capable ofhandling relatively high pressures with low leakage.

A more specific object is to minimize the resistance to operatingmovement of a pressure-sealed plate type valve.

Other more specific objects and features of the invention will appearfrom the description to follow.

ln its simplest and most commonly used form a plate valve consists of axed and a rotatable disk having ground and lapped iiat surfaces sealingagainst each other, the surfaces containing cooperating ports movableinto and out of registration with each other in response to rotation ofthe movable disk. To reduce or prevent leakage the rubbing surfaces ofthe disks must not only lit, i. e. be at, but must be pressed togetherwith a force greater than the separating force of the pressure fluid inthe ports. Excessive force is undesirable because it increases thefrictional resistance to rotation. It has been found desirable inpractice to develop the sealing force by applying the Huid pressure inthe ports to a portion of the rear face of the movable disk so that thesealing force is proportional to the separating force regardless v ofvariations of pressure in the fluid. Unfortunately, however, even thoughthe uid pressure remains constant the separating force varies indifferent positions of the valve due to the fact that when cooperatingports are in partial registration the opposed areas between the disks towhich the pressure is applied are greater than when the ports are inregistration. The result is that much` greater force is required to turnthe valve in the positions of port registration than in the positions ofport overlap.

This defect is reduced in accordance with the present invention byproviding means for applying sealingpressure to properly located areasof one of the disks during port overlap and removing this pressure inpositions of port registration.

Another defect of prior known plate type valves is that even relativelyheavy thick disks are capable of suiiicient distortion under highpressures to permit excessive leakage between the disks. l

This defect is corrected in accordance with the invention by making theport edges thin and reentrant so that they are capable of distorting(bending) in response to pressure in the ports to seal with theropeningdisk even though the disks do not seal with each-other at all otherareas.

Fig. 2 is a longitudinal vertical sectional view through the valve takenin the plane II-II of Fig. 1;

Fig. 3 is a longitudinal horizontal sectional View through the valve thesection being taken in the plane IlI-III of Fig. 2;

Fig. 4 is a detail section taken in the plane IV-IV of Fig. 1;

Fig. 5 is an enlarged detail sectional view taken through one of theports in the valve;v

Fig. 6 is a cross sectional view taken in the plane VI-VI of Fig. 2; v

Fig. 7 is a longitudinaly sectional View taken in the plane VII-VII ofFig. 6; and

Figs. 8, 9, and l0 are cross sectional views taken in the planeVIII*VIII of Fig. 2 and showing thel valve in three diiferent positionsof operation.

Referring iirst to Fig. l there is disclosed a conventional hydraulicsystem consisting of a reservoir 15, a pump 16, a pressure relief Valve17, a selector Valve 18 in accordance with the invention, and a motor 19to be selectively actuated in one direction or the other by manipulationof the selector valve 18. Thus the valve 18 is provided with a pressurepassage 20 which is connected to the output of the pump 16, a returnpassage 21 which is connected to the reservoir 15, a motor passage 22connected to one end of the motor cylinder 19, and a second motorpassage 23 connected to the other end of the motor cylinder 19. Thevalve 18 has a neutral and two active positions. In the neutral positionthe valve isolates the motor passages from the pressure passage' and thereturn passage. In this position of the valve the blocking of the motorpassages 22 and 23 locks the motor 19in whatever position it happens tobe in. In a first active position, the valve 18 has its pressure passage2i) connected to the motor passage 22 and has the other motor passage 23connected to the return passage 21, so that pressure uid from the pump16 is delivered to the left end of the motor cylinder 19, and fluid isexhausted from the right end of the motor cylinder back to thereservoir. In the second active position of the valve the pressurepassage 20 is connected to the motor passage 23, and the motor passage22 is connected to the return passage 21, so that duid from the pump isdelivered to the right end and lluid is exhausted from the left end.

Referring to Fig.V 2, the valve 18 comprises a cup shaped casing 25closed at'its rear end by a cover plate 26 which may be secured in placeby screws 27 and sealed with respect to the case 25 by a sealing ring28. The casing 25 and the cover plate 26 define a cylindrical chamber 29containing a iixed valveplate in the form of a disk 30 and a rotatableplate in the form of a disk 31. 'The disk 30 is fixed only in the sensethat it is not free to rotate within the chamber 29. However it is freeto move to a limited extent longitudinally within this chamber towardand away from a backing face 33 `in the casing 25 which constitutes thefront wall of the cylindrical chamber 29. On the other hand therotatable disk. 31 is not free to move longitudinally between the disk30 and the cover plate 26 because it is supported with respect to thecover plate 26 by a ball thrust bearing 34.

`To rotate the disk 31, there is provided an actuating shaft 36 whichextends through a bore 37 provided therefor in the casing 2S and throughcorresponding central y A full understanding of the invention may be hadfrom the following detailed description when read' in connection withthe drawing, in which:

Fig. l is a schematic diagram of a hydraulic system incorporating aselector valve constructed inY accordance withthe invention, the valvebeing shown inelevation;

bores in the disk 30 and the disk 31. Adjacent its inner end the shaft36 is provided with a cross pin 38 which projects beyond the surface ofthe shaft into a slot or keyway 39 in the disk 31 whereby the latterdisk can be rotated by rotating the shaft 36. At its right end, exteriorof the casing, the shaft 36 is provided with ats 40 for the attachmentof a suitable actuating handle. To seal against iluid leakage betweenthe bore 37 of the casing 25 and the shaft 36 a sealing ring 42 may beprovided in an annular groove 36a in the shaft.

The pressure, return, and motor passages of the valve 18 previouslyreferred to in connection with Fig. 1 communicate respectively with fourlongitudinal passages 20a, 21a, 22a, and 23a in the casing body, whichlatter passages are symmetrically disposed about the center bore 37 andregister with corresponding ports extending through the fixed plate 30.

Thus the return passage 21a communicates with a return port 43, thepressure passage 20a communicates with a pressure port 44, the motorpassage 23a communicates with a motor port 45 and `the motor passage 22acornmunicates with a motor port 46. The expression pressure port as usedherein means the port in which the pressure is always as high or higherthan in any other port.

No effort is made to provide a seal between the return passage 21a andthe return port 43 in the disk 30 because minimum pressure exists inthese passages. However all of the other three passages in the casing 25are sealingly connected to their associated ports in the disk 3l). Thesealing construction is the same in each instance and will be describedwith reference to that associated with the port 44 and passage 20a inFig. 2. Thus the disk is provided with a bore 48 which has weldedtherein a sleeve 49, the outer end of which projects into the passage20a in slide fitting relation therewith. The left end of the passage 20ais counterbored to receive a sealing ring and a pair of backing members51 and 52, so that pressure tluid tending to leak from the passage 20aaround the outside of the sleeve 49 is blocked by the ring 50. Thestructure described provides for a seal between the ports 44, 45 and 46in the disk 30 and the corresponding passages 20a, 22a and 23a in thecasing 25, while permitting limited longitudinal or axial movement ofthe disk 30 with respect fo the casing.

As best shown in Fig. 5 the left ends of the ports 44, 45 and 46 in thedisk 30 terminate in thin reentrant edges 56 at the contact surface ofthe disk 30 which bears against the rotatable disk 31. Pressure fluid inany one of the ports 44, 45 or 46 urges the thin edges 56 against thedisk 31 to improve the seal therebetween.

The rotatable disk 31 has in its sealing face 31a (Fig. 7), two ports 60and 61 (Fig. 8) interconnected by a passage 62 in the disk, and twoports 63 and 64 interconnected by a passage in the disk. In the neutralposition of the valve shown in Fig. 8 the ports 60, 61, 63 and 64 arepositioned midway between the ports 43, 44, 45 and 46 in the fixedplate, so that the latter ports are isolated from each other. When therotatable plate is rotated clockwise 45 from the position shown in Fig.8 into the position shown in Fig. l0, the ports in the rotatable plateregister with ports in the fixed plate so that passage 62 connects thereturn port 43 in the fixed plate to the motor port 45, and the passage65 in the rotatable plate connects the pressure passage 44 in the fixedplate to the motor port 46, to deliver pressure fluid to the left end oft'he motor 19 (Fig. l) and exhaust fluid from the right end thereof.

If the rotatable plate is rotated 45 counterclockwise from the positionshown in Fig. 8 the passage 65 connects the return port 43 in the fixedplate to the motor port 46, and the passage 62 connects the pressureport 44 to the motor port 45, to actuate the motor 19 in the oppositedirection.

To limit motion of the rotatable shaft 36 and the rotatable disk 31, acollar is secured to the shaft 36 at the front end of the case 25, andthe case is provided with a detent ball 71 (Fig. 4) urged outwardly by aspring 72, and with a stop pin 73. The collar 70 is provided with threeholes 74, and 76 which register with the detent 71 in the threepositions of the rotatable valve to yieldably retain tbe rotatable diskin the desired positions. The pin 73 is adapted to cooperate with a pairof shoulders 77 and 78 on the collar 70 for preventing rotation of therotatable disk beyond the open positions.

In the neutral position of the valve as shown in Fig. 8 all the ports inthe fixed plate 30 are closed by the rotatable plate 31. Pressure fluidin any of these ports will leak away from the ports between the twoplates to an extent dependent upon the accuracy of the fit between thetwo plates, and a separating force will be produced between the twoplates by the leakage fluid. By carefully lapping the surfaces of theplates the leakage can be held down to such value that the separatingforce resulting therefrom can be made less than the sealing force of thepressure lluid in the ports acting against the flange 56 and the seals50, so that an effective seal is obtained in neutral position. Thepressure forces tending to separate and oppose separation of the platesin either of the fully opened positions of the valve are the same as inthe neutral position.

However the separating forces increase in positions intermediate thefully opened and fully closed positions, in which the ports in one platepartially overlap the ports of the other plate. Thus in Fig. 9 theoverlap of the pressure port 44 with the port 64 and of the port 63 withthe port 46 produces pressure in all of these ports, and thc separatingforce resulting from the pressure in the ports 44 and 46 in the fixedplate is supplemented by the separating force of the same pressure inthe ports 64 and 63 in the rotatable plate. Hence more sealing force isrequired to overcome the separating force in positions of partialoverlap of the ports than in positions of full overlapV (registration)and of no overlap.

Heretofore, separation of the plates by the increased pressure forcesduring partial overlap has been prevented by permanently applyingpressure to a rear face or faces on one of the plates of sufficient areato develop a sealing force exceeding the maximum separating force inintermediate positions. This is objectionable because it undulyincreases the resistance to rotation in the fully opened and fullyclosed positions of the valve.

In accordance with the present invention there is applied a pressure tothe rear faces of the fixed plate through ducts in the face of the xedplate that are connected to ports in the rotatable plate only inintermediate positions of the latter.

Thus referring to Figs. 6 and 7 the fixed plate 30 has four cylindricalrecesses 80, 81, 82 and 83 extending .into the plate from the rear facethereof, and each contains a piston 84 sealed by a sealing ring 85. Eachpiston abuts against the face 33 of the casing 25 so that pressure inthe associated recess acts against the inner end of the recess to urgethe plate 30 away from the casing face 33 and toward the plate 31 with aforce proportional to the pressure and the area of the inner end of therecess. Each recess is connected by a small duct 87 to a groove 88 inthe sealing surface 30a. The four grooves 88 are positioned between butend short of the ports .in the xed plate and lie in the paths of theports in the rotatable plate. The grooves 88 are shown straight andnormal to radii drawn from the duets 87 for ease of manufacture but theywould function as well or better if they were arcuate in shape about theaxis of rotation.

There are also formed in the face 30a of the fixed plate 30 four fineradial grooves 89 extending from the inner to the outer edges of thefixed plate and intersecting the grooves 88 at the ducts 87. The grooves89 are much smaller than the grooves 88 so that they oler substantialresistance to nid ow therethrough and serve to provide paths for thedrainage of pressure fluid from the grooves 88 and the ducts 87 when thegrooves 88 are not in lapping relation with a pressure port. Fluiddraining through the grooves 89 can escape to the return port or passage21a in the casing (Fig. 2) since this passage is not sealed with respectto the port 43 in the fixed plate as are the other ports in the fixedplate.

It will be observed from inspection of Fig. 8 that all of the grooves S8are spaced from the ports in the fixed plate and are in registrationwith the ports in the rotatable plate. By virtue of the leakage pathsthrough the fine grooves 89, pressure is dissipated from all of theports in the rotatable plate.

Referring now to Fig. 9, the rotatable plate is shown rotated inclockwise direction .into a position where the ports therein just beginto lap the ports in the fixed plate, thereby admitting any pressurefluid that may be in the ports in the fixed plate into the portsA in themovable plate. In this position the ports in the movable plate alsoregister with the grooves 88. Pressure uid therefore flows from theports in the rotatable plate into the grooves 88 faster than it can bedissipated therefrom through the line return grooves 89, so thatpressure is applied through the ducts 87 to the recesses 80 to developpressure against the inner ends of those recesses tending to urge thexed plate more strongly against the movable plate and overcome theadditional separating force developed between the plates because of theadditional port area that is exposed to pressure.

This condition prevails until the ports in the rotatable plate closelyapproach full overlap or registration with the ports in the fixed plate,at which time the ports in the rotatable plate leave the grooves 88.This permits the pressure in the recesses 80 to be dissipated by leakagethrough the ducts 87 and the radial grooves 89 into the casing, therebydissipating the pressure urging the fixed plate against the rotatableplate so that the resistance to rotation of the valve is reduced in thefully opened position.

When the valve is next returned to neutral by counterclockwise rotationof the rotatable plate 31 from the position shown in Fig. 10 toward theposition shown in Fig. 8 the ports 60, 61, 63 and 64 approach the endsof the grooves S8 so that the leakage paths between the lapped surfacesof the plates from the ports 64 and 63 to the grooves 38 are shortenedprior to the time when the ports actually begin to lap the grooves. Thisgradually .increasing leakage flow into the grooves gradually raises thepressure in the recesses 80 to compensate for the increased separatingforce between the plates due to the departure from full registration ofthe ports in the rotatable and xed plates respectively. The result isthat when the ports in the rotatable plate do begin to lap the grooves88 there is not a violent sudden increase in pressure in the recesses8i) to 83.

it will be noted from inspection of Fig. 2 that the return port 43 inthe fixed plate 30 is counterbored at its left end so that the effectivediameter of this port in the surface 30a is greater than that of theother ports. This is often desirable because it causes connection of onemotor port to the return line slightly before the other motor port isconnected to the pressure line. This enlargement of the return portnecessitates the shortening of the two grooves S8 adjacent thereto asbest shown in Fig. 6.

Although for the purpose of explaining the invention, a particularembodiment thereof has been shown and described, obvious modiiicationswill occur to a person skilled in the art, and I do not desire to belimited to the exact details shown and described.

I claim:

1. A' valve comprising: casing means containing first and secondrelative slidable members having cooperating contact faces adapted tosubstantially seal with each other when pressed together, and means forrelatively sliding said members between a neutral and an active positionwith respect to each other; means supporting said first member againstmovement with respect to said casing in direction away from the secondmember, the second member having a rear side lopposite its contact face,and said casing having a backing face juxtaposed to said rear side andspaced therefrom; said iirst member having a iuid tiow passage thereinterminating in a port in its contact face and said second member havinga pressure passage therein terminating Vin a pressure port in itscontact face, the said ports being so positioned as to register witheach other in said active position of said members and be displaced fromeach other in said neutrali position; means defining a pressure chamberresponsive to pressure therein for developing thrust between said Secondmember and said backing face of said casing for urging said secondmember against said tirst member; and said second member having a ducttherein connecting said pressure chamber to a portion of thecontact'face of the second member in the path of the port in said firstmember and adjacent to but spaced from the said pressure port in thesecond member whereby: fluid can tiow from the pressure port in saidsecond member to said pressure chamber only through a leakage pathbetween said faces from said pressure port in said second member to saidduct in said neutral position of said members, the leakage path isshortened by overlap of the port in said first member with said ductduring approach of the ports in said two members toward each other, saidpressure chamber is directly connected to both said ports while saidport in said lirst member is overlapping both said duct and the pressureport in said second member, and fluid canflow from the pressure port insaid second member to said pressure chamber only through a leakage pathof increasing length between said surfaces from the port in said firstmember to said duct as the port in the first member moves fromoverlapping relation with said duct into full registration with thepressure port in said second member.

2. A valve according to claim l in which said portion of the contactface of said second member is delined by a groove in said contact'faceconnected to said duct and` extending in the direction of relativemovement between said members.

3. A valve according to claim l in which said contact face of saidsecond member contains a iine groove extending from said duct to amargin of said contact face and defining a bleed path for controlledflow of iiuid from sai pressure chamber.

4. A valve according to claim 1 including means defining a bleed pathfor dissipating pressure in said chamber.

5. A valve according to claim l in which said pressure port in saidsecond member has an inwardly extending thin fiange the outer face ofwhich defines the portion of said contact face immediately surroundingsaid port and the opposite face of which is exposed to pressure in saidport.

6. A valve according to claim 1 in which said means defining` saidpressure chamber comprises a recess in the rear side of said secondmember and piston means closing the outer end of said recess andabutting against said backing face of said casing.

7. A valve according to claim l in which said first member has a secondport in its contact face connected to the other end of said fluidpassage therein; said second member has a second port, and means forconnecting said iirst mentioned and second ports in saidv second memberto an external iiuid line; said duct connecting to that portion of thecontact face of said second member intermediate the said ports therein.

8. A valve according to claim l in which: said members are relativelyrotatable about an axis normal to their contact surfaces; said iirstmember has, in addition to said rst mentioned port, second, third andfourth ports all symmetrically located about said axis, and asecond'passage, the first and second ports being adjacent each other andinterconnected by said iirst mentioned fluid passage in said firstmember, and the third and fourth ports being interconnected by saidsecond passage; said second member has in addition to said rst mentionedport second, third and fourth ports so located as to registerrespectively with the four ports of the rst member in said activeposition of said member and Vbe isolated therefrom bythe Contact face ofthe rst member in said neutral position; means dening second, third andVfourth pressure chambers responsive to pressure therein for developingthrust between said second member and said backing face of said casing;and second, third and fourth ducts in said second member connecting saidsecond, third and fourth pressure chambers respectively to diierentportions of the contact face of the second member in the Vpaths of saidsecond, third and fourth ports in said tirst member, said pressurechambers and ducts be circumfcrentally disposed between said ports insaid second member in juxtaposed relation to the respective ports ofsaid rst member in said neutral position of said members.

9. A valve according to claim 8 in which said easing defines fluidpassages registering with said ports in said second member; meansconnecting three of said ports in said second member in sealing relationwith their associated registering passages in said casing, the fourthport and registering passage being in communication with the f spacebetween said casing and said members.

lO. A valve according to claim l in which said easing de'nes a uidpassage extending thereinto from 'said backing face; said second membercomprises a sleeve extending therefrom into said casing passage intelescoping relation therewith and communicating said pressure fluidpassage in said second member with said casing passage, and meanseffecting a iluid seal between said sleeve and said casing passage, saidcasing passage being of larger cross-sectional area than said pressureport, whereby d pressure in said passage urges said second member towardsaid rst member.

l1. A valve comprising easing means containing a rotatable member and anon-rotatable member, said members having cooperating contact facesadapted to substantially seal with each other when pressed together;means for rotating said rotatable member between a neutral and an activeposition; means supporting said rotatable member against movement withrespect to said casing in direction away from said non-rotatable member,the latter having a rear side opposite its contact face and having anintegral sleeve projecting from said rear side, and said casing having abacking face juxtaposed to said rear side and spaced therefrom, and aliuid passage extending through said casing from said backing face andreceiving said sleeve in telescoping relation; said rotatable memberhaving a fluid flow passage therein terminating in a port in its Contactface, and said non-rotatable member having a pressure uid passagetherein communicating with said sleeve and terminating in a pressureport of reduced diameter in its contact face, the said ports being sopositioned as to register with each other in said active position ofsaid rotatable member and to be displaced from each other in saidneutral position; and means effecting a uid seal between said sleeve andsaid casing passage, said casing passage being of larger area than saidpressure port, whereby pressure in said casing passage and said sleeveurges said non-rotatable member toward said rotatable member; saidsleeve telescoping part way into said pressure Afluid passage in saidnon-rotatable member and being rigidly joined thereto for movementtherewith; and said pressure uid passage having an inwardly extending,pressure-deliectable, thin ilange at the contact face end thereof, saidflange dening said pressure port of reduced diameter in said contactface.

References Cited in the tile of this patent UNITED STATES PATENTS2,317,407 Samiran Apr. 27, 1943 2,578,160 Van Der Werff Dec. 11, 19512,653,003 Overbeke Sept. 22, 1953

